Remember rolling into an old-fashioned drive-in and ordering food and a root beer to enjoy right in your car?

These past few decades, drive-in diners have become as scarce as drive-in theaters, eliminated by a fast-paced society in favor of drive-through windows and eat-in fast-food restaurants.

But one drive-in stalwart is planning a big comeback.

Oklahoma City-based Sonic unveiled plans in an exclusive interview with The Star to open 75 franchises over the next 10 years in Central Indiana, from as far south as Bloomington to as far north as Lafayette. A wider rollout still being planned could add another 75 Sonic restaurants elsewhere in the state over the next decade.

Sonic, which has been around for 60 years, has 3,500 locations. Seventeen of those are already here in Central Indiana, including Avon and Camby.

Sonic plans to open 1,000 drive-in diners nationwide over the next decade, in markets that include Atlanta and wide stretches of California and Florida.

Patrick Lenow, Sonic's vice president of media relations, said a national advertising campaign has grown demand for Sonic in new and underserved markets, such as the Indianapolis area.

You've seen the TV spots, two child-like guys who have oddball conversations while ordering and doing goofy things, such as ordering every shake that Sonic offers. Lenow says Sonic already is the sixth-largest buyer in the Indy market among fast-food restaurants.

"We have demand growing and building," Lenow said. "We have customers asking us when are we going to put more stores in the marketplace. Our goal is to be within 10 minutes of every customer in the United States."

Steve Bailey, a longtime Fishers resident, is leading the expansion as Sonic's senior director of franchise development.

Bailey said Indianapolis has "a very strong, stable economy. It's got friendly people and there's a great opportunity here. I think Indianapolis is one of the best cities in the United States. ... and I believe Sonic is a fantastic match."

The new Sonic restaurants, which likely will begin opening in the Indianapolis area as soon as 2015, will feature age-old car ports that Bailey says bring back a lot of "nostalgic memories."

But in a nod to changing times — and cold-weather cities such as Indy — Sonic will add drive-through windows and eat-in seating, too, to make sure customers have their choice of dining options.

Sonic is seeking local franchise owners. Investors need to have $500,000 in liquid capital, a $1 million net worth and funds to construct a restaurant, estimated at costing $1.1 million to $1.6 million.

Drive-in diners have become scarce in Indiana, but they're not gone entirely.

In addition to Sonic, competitor Dog n Suds still has three Indiana locations left, in Lafayette, West Lafayette and Fort Wayne. And The Suds, a locally-owned drive-in, operates in Greenwood.